TYPES OF WATER HEATERS:
Tank-type water heaters (gas & electric powered) are the most common. They heat water before you need it and store it in the tank. They are available in a wide range of sizes from 6 gallon to 120-gallon storage capacity. The most common size and least expensive, based upon cost per gallon, is a 50-gallon size. A 50-gallon water heater can be installed for the same price as a 40-gallon size for example. A newer water heater will typically be better insulated than an older model. The preferred fuel is natural gas as it is cheaper to operate over time than an electric model. New gas water heaters have more options than the old and they have been re-designed to minimize igniting flammable vapors, which may be present in basements, workshops or garages due to paint fumes or leaking gasoline from a parked car.
Tankless (instant hot water, continuous or on-demand water heaters) have no storage tank as they heat water only when the faucet or shower is turned on. This type of heater is popular in Europe and is just becoming a popular option here in the USA in the last few years. They come in both gas and electric models however the gas models are much more popular for whole-house water heating. Most are supplied with electronic ignition, doing away with the old standing (running) pilot. Tankless models cost more than storage types and are more complex in their design. Tankless type water heaters must be sized correctly to function as intended. A specialist is recommended for installation. Once installed and sized properly a tankless type water heater can truly supply “endless hot water” continuously.
Heat Pump Water Heaters are not as popular however they may be worth checking into when gas is not available as they use much less electricity to heat the water than conventional electric resistance elements. This type of water heater removes heat from the surrounding air and puts it into your water. (Think of your refrigerator – it moves the heat out of the fridge to the outside air). One of the potential advantages (or disadvantage) is the fact that it cools and dehumidifies the air in the room the heat pump is located in. This can be a great advantage in the summer or in basement areas that can benefit from dehumidification. (The winter is a different story- I would locate the equipment where outside air can be exchanged). You can save 50% to 65% on your electric bill compared to typical tanks! This is a good option when the water heater is in the same room with an old hot water boiler, refrigeration compressors or other incidental heat sources.
Indirect water heaters use hot water from a boiler to heat the water in a tank. If you already have a hot water heat system it can provide the hot water you need for your domestic use as well. The hot water from the boiler is circulated through a heat exchanger inside the indirect tank thus heating the domestic water. Indirect tanks last much longer than normal storage type heaters as the heat source is not in or under the tank (that’s why we call them indirect tanks). You get the benefit of your newer boiler’s efficiency that can be as high as 99%! The volume of hot water production is typically much more than a conventional water heater. It can be as much as 200 gallons per hour compared to 40 or 50. If you have a hot water boiler heating your home it is worth looking at the possibility of using it to heat your domestic water with this type of tank.
Combination Domestic Hot Water & Space Heating – These machines combine both the domestic hot water for your shower and a space heating hot water maker for heating your house with radiant. The cost is typically less than two separate hot water making devices and can significantly save space because you do not need both a hot water boiler and a water heater. When space is at a premium, these units are a great choice. They typically cost less than installing both a water heater and a boiler. Fuel efficiency is greater than 90%.